Previous comparisons of a virus from the insect Amsacta moorei with other viruses indicate that it most closely resembles poxviruses of vertebrates, and in some characteristics (e.g., morphopoiesis and enzymes), it is markedly similar. Several similar viruses have been described in recent years, but none have proved as amenable to laboratory study as the one from A. moorei. Characterization of these viruses lags far behind that of vertebrate poxviruses. This type of information is needed to establish the degree of relatedness of vertebrate and insect poxviruses and relatedness within the insect poxvirus group. Insect poxviruses are being seriously considered for insect control, but vertebrate susceptibility is poorly documented and needs study. The principal objectives of the proposed research are (a) to characterize the virus from A. moorei and (b) to compare the physical, chemical, morphological, and biological (particularly pathological) characteristics of this virus with those of vertebrate poxviruses and with other insect viruses. Specific aims include (a) comparing proteins of two insect and one vertebrate poxvirus by gel electrophoresis and serology, (b) partially characterizing viral DNA, (c) following pathophysiological (DNA and protein synthesis) changes in infected hosts, (d) examining the replicative cycle and fine structure of virions, (e) testing for susceptibility to inhibitors of vertebrate poxviruses and for ability to reactivate with other poxviruses, and (f) establishing a new insect tissue culture line, and checking this line, established lines from other insects, and vertebrate lines for susceptibility to the virus.